Heretofore, it has been well known in the building and construction industries to attach sheets of insulation or insulation board to an erected building substrate such as gypsum, concrete, or other masonry. The sheets of insulation are applied uniformly to the entire substrate of the building for insulation purposes. An aesthetic, waterproof, and impact-resistant finishing material or system is generally applied over the insulation. One example of such an application is the "THOROWALL" system in which the insulation is an Expanded Poly-Styrofoam, commonly referred to as "EPS." "THOROWALL" is a trademark owned by Thoro System Products. Besides EPS, there are numerous types of sheet insulation material including different types of styrofoam available for use in building construction. The EPS sheets are generally light in weight, approximately one pound per cubic foot, and their dimensions vary, although a standard size is two feet wide by four feet long with a thickness of one, two, or more inches. When affixed to a building substrate, the longer dimension of the sheets extends horizontally.
Although the finishing material is waterproof, moisture has a tendency to buildup between the insulation and substrate. To eliminate this moisture problem, the construction industry has developed and employed sheet insulation having spaced apart drainage channels along the shorter dimension of the sheets such that the channels are vertically disposed on and adjacent to the building substrate to funnel downwardly the moisture trapped between the substrate and the insulation. One example of the channeled sheet insulation is the "INFINITY" system in which the insulation includes beveled edges and vertically extending (i.e., when installed) drainage channels. "INFINITY" is a trademark owned by Dryvit Systems Inc.
While mechanical fasteners have been used to attach this type of sheet insulation to a substrate, a common method has been to apply adhesive or glue to the sheets of insulation to adhesively secure the insulation to an erected building substrate. Several types of adhesives are commercially available, some being more suitable to different substrates, different types of insulation, and differing climates. Also, it has been known to mix some adhesives with cement.
Heretofore, adhesives have either been manually applied to sheets of insulation or applied by adhesive-applying machines such as shown in U.S. Pat. No. 5,421,887. However, such machines are ineffective in applying adhesive to sheets of insulation having transversely spaced apart drainage channels because the machines would deposit adhesive into the drainage channels thereby blocking the drainage channels, which is undesirable. Moreover, even the manual application of conventional adhesives to sheets of insulation having drainage channels may result in the adhesive flowing into the channels when the insulation is pressed against the substrate, thereby blocking or closing the channels. Accordingly, there is a need for an adhesive which does not flow into the drainage channels when the insulation is pressed against the substrate and for an apparatus for applying the improved adhesive to a series of sheets of insulation having drainage channels and to additionally provide airflow passages between channels, while preventing the improved adhesive from entering the drainage channels.